1. Field of the Invention:
The invention relates to the insertion or installation of foundation piles into the ground, and particularly to a rotational device for accomplishing such installation.
2. Description of the Prior Art:
The installation of conventional foundation piles has previously been accomplished by drilling a hole in the ground, as by an auger, and lowering a premolded pile into the hole. After drilling the hole, loose dirt often remains in the bottom of the hole, preventing the pile from being inserted completely to the desired depth using only the weight of the pile itself. Therfore, it is necessary to rotate the pile and press it downwardly.
Therefore, in the conventional methods, a device has been attached to the head of the pile to rotate it, using the same source of power that was used for rotating the auger. In using this method, it has been difficult to transfer rotational force or torque applied to the head or upper portion of the pile through the length of the pile to its lower end. The transmission of this torque through the pile was hampered by friction of the ground against the pile, and the degree of settlement that may be achieved using this method has been limited. The problem also has become more difficult to employ with relatively long piles. In addition, the torque applied to the upper portion of the pile may cause shearing failure of the pile itself, which is usually made of concrete. The chances of such failure become greater with increasing length of the pile.